Increasing transmission efficiency would cut air pollution

Investment in electrical transmission and distribution (T&D) systems could significantly reduce air pollution, according to a study led Lauren Janicke, an undergraduate in civil and environmental engineering (CEE), and Destenie Nock, assistant professor of CEE and engineering and public policy. Published in Energy, the researchers measured the air pollution generated through inefficiencies in T&D networks, examined opportunities for reducing emissions through regulation at the multinational and sub-national scales, and compared the cost of these potential emissions reductions to the cost of investment in renewable energy.

Janicke, Nock, and their co-authors note that, “globally, 10.2 million premature annual deaths can be attributed to fossil-fuel generation and associated PM2.5 emissions (fine inhalable particles less than 2.5 millionths of a meter in size), a large part of which comes from the electricity sector.” When there are inefficiencies in the electrical system, more energy must be produced to compensate, resulting in excess emissions from what they term “compensatory generation.” There are well-explored opportunities for reducing emissions from the way we generate and consume electricity; however, comparatively little research exists on the potential for reducing air pollution incurred in the delivery of electricity from the generator to the consumer.

By comparing the electricity generated in a given country to the electricity delivered to end users, Janicke and Nock quantified the percentage of emissions resulting from compensatory generation in 142 countries. They found great variation in these, ranging from as low two percent of total generation lost in Singapore, to as high as 60 percent of total generation in Haiti, and reaching five percent in the U.S. This has an especially strong impact on air pollution for countries reliant on carbon-intensive energy sources. On a global scale, around 2100 Terrawatt of compensatory generation is required due to these T&D losses.

In analyzing several scenarios, the team found that improving T&D efficiency between five and 33 percent would decrease global median emissions by as much as 40 percent. The efficacy of emissions reductions within different scenarios varies by pollutant type, and the type of generation prevalent, particularly coal or oil, also correlates with opportunities for emission reductions due to compensatory generation.

In the U.S. there are multiple subnational regulatory bodies, the most prominent being the North American Electric Reliability Corporation (NERC), which works under federal oversight to develop and enforce reliability rules for bulk power electric transmission systems. The different regions within NERC present different energy profiles, meaning different opportunities for reducing T&D losses. Overall, the high ambition scenario for regulation (five percent cap on losses) could cut compensatory generation on average by about 60 percent—about three percent of total U.S. power generation. The source from which states generate their energy again influences its potential for reductions in emissions through increased T&D efficiency. State policy also plays a major role, with states like North Dakota (heavily coal-dependent) and Texas (natural-gas dependent), for example, having opportunities at the state level that could significantly decrease emissions from compensatory generation.

T and D losses will not completely compensate for relying on fossil fuels, but it can reduce current emissions as we are transitioning and reduce the total amount of renewable generation we will need to build.

Destenie Nock, Assistant Professor, Engineering and Public Policy and Civil and Environmental Engineering

“It is important to recognize that while improving T&D losses will not completely compensate for relying on fossil fuels, it can reduce current emissions as we are transitioning, and reduce the total amount of renewable generation we will need to build,” notes Nock.

Regarding T&D losses themselves, they distinguished between technical losses, resulting from infrastructure inefficiencies, and non-technical losses, resulting from theft or error. Janicke and Nock note that technical losses could be eliminated by replacing older T&D infrastructure with newer, high-voltage lines. Likewise, non-technical losses could best be cut down by reducing electricity theft, deploying smart meters, and enforcing greater accountability in bill payment. In a cost comparison per ton of CO₂ abated, they found that smart meters in the U.S. have a median abatement cost of $1,100 per ton CO₂, compared to $700 per ton CO₂ for wind turbines, and $1,280 per ton carbon dioxide (CO₂) for solar plants. However, cost estimates for mass deployment of smart meters still need to be performed, and renewable energy is dependent on weather conditions. Janicke and Nock estimate that in a moderate ambition scenario for the U.S. with a cap of 33 percent current T&D losses, wind turbines would be most cost-effective; however, in the high ambition scenario capped at five percent, smart meters become more cost-effective. Smart meters may also have a greater impact in other regions of the world where non-technical losses are higher, in combination with automated billing.

“We note that countries are using a combination of approaches (smart meters, wind, and solar deployment) as part of their decarbonization strategies,” the team concluded. “Smart meters might be cheaper in some cases, and the right combination of smart meters, wind, and solar should be based on spatially resolved analysis. While renewable energy has other benefits beyond reducing carbon emissions, even in a high renewable future, smart meters will be beneficial because they will reduce the electricity demand, leading to fewer investment needs in generation capacity.”